Raphael josia



UNITED STATES ATENT FFICE,

RAPHAEL JOSIA, OF FLORENCE, ITALY, ASSIGNOR TO WILLIAM REY AND C. DEVARIGNY, BOTH OF PAR-IS, FRANCE.

COMPOSITION FOR TREATING SULPHATES OF LIME FOR THE MANUFACTURE OFARTIFICIAL MARBLE.

SPECIFICATION forming part of Letters Patent No. 265,507, dated October3, 1862.

Application filed August 9, 1882. (N specimens.)

To all whom it may concern:

Be it known thatLRAPHAEL JosrA, of Florence, Kingdom of Italy, haveinvented or discovered a new and useful Improvement in Oompositions forTreating Sulphates of Lime for the Manufacture of Artificial Marble; and[do hereby declarethe following to be afull, clear, concise, and exactdescription thereof.

In an application for Letters Patent of the United States filed March 2,1882, I have described and made claim to an improved process of treatingor preparing gypsum (calcic sulphate or sulphate of lime) in the makingof articles of a material which I have termed I5 certaldite withoutpulverization of the gypsum. In said application I described brieflycertain ofthe compounds or compositions which I employ to producecertain effects and the manner of using them, but stated that separateapplications would be made for patents for such compositions.

The present application relates to one of the compositions (a double ortwo-part one) so referred to, the two parts being designed for alternateuse as two separate baths in the process herein described for makingyellow certaldite.

Incarrying out the process referred to a suitable piece of gypsum(calcic sulphate) is 0 first formed into the desired shape, orapproximately such, by the use of suitable well-known tools. The gypsumemployed may be the ordinary native gypsum of commerce, though I preferthat which is comparatively pure or free 5 from other matters ofdifi'erent composition. Such gypsum is usually obtained hydrated, orcontaining a certain percentage of water in its composition; and thesecond step in the operation has reference to depriving the gypsum 0under treatment of a considerable part or the whole of such water. Thisis done by subject.- ing it to the action of a gradually-increasingheat, varying by preference with the size and quality of the material,from 260 to 300 5 Fahrenheit, for about twelve hours, or until thedesired partial. or complete dehydration is obtained. The length oftime, as well as the degree of heat required to effect this result, willvary somewhat with the size, character, and purity of the gypsumemployed; but

the temperature should not exceed 500 Fahrenheit, and both it and thetime of exposure should be regulated and limited with reference tosecuring uniformity of treatment throughout the whole mass or body. Thisoperation may be known to be complete when a fracture of a test blockpresents a uniform white color. Any suitable drying or baking apparatusmay be employed for this purpose, many such being known in kindredbranches of the arts; butit should be of such construction that thematerial under treatment shall not be brought into direct contact withthe lire. When the desired dehydration has been effected the furnace isallowed to cool gradually,in order that the material under treatment maybe cooled gradually; or the material may be removed, with due care toprevent breaking and exposure to moisture, and allowed to cool outsidethe furnace gradually until it is reduced in temperature snfficiently topermit handling with safety in its subsequent treatment, which isdesigned to impart to it the desired color or tint and a high degreeofinsolubility and hardness throughout its mass. Thisstep involves theuse of the two-part composition which forms the subject-matter ofinvention 1n the presentapplication. The parts of this com positionareformed ofthefollowingelements: First part: water, by weight, twohundred parts; sulphate ofiron, by weight, six parts. Second part:water, by weight, two hundred parts; alum, by weight, four to 'fiveparts; oxalic acid, by weigh wsqjtwo and a half parts; bichromateofpotash, by weight, two parts. The ingredients of each of these partcomposi-- tions, being mixed in about the proportions named, formsolutions which are used as separate baths; and to this end they areplaced in separate vessels of proper shape to receive the article to betreated, which is dipped or immersed first in one and then in the otherany desired number of times, and then is permitted to remain in the bathcontaining the sulphate of iron until the article has acquired thedesired degree of hardness and color. The length of time required toeffect this result will depend somewhat upon the strength of theingredients composing the bathsor solutions, the porosity and nature orphysical and chemical condition of the article under treatment; butusually twelve hours (more or less) will snffice. In the alternatetreating of the article in the separate baths above described I preferrepeated dippings -two, three, or more-say two or three seconds atfirst, and increasing gradually to one, two, three, or more minutes,more or less, with drying intervals of like increasing length betweendippings, for half or threequarters of an hour or so, after which thearticle may remain in the bath containing the sulphate of iron eleven ortwelve hours, more or less.

\Vhile I do not limit my invention by any particular theoryof chemicalor physical reactions involved in the use of these baths as abovedescribed, I believe, with my present knowledge, that the metallic saltsheld in so lution in each bath,by taking the place of the molecules ofwater displaced in the previous dehydratingoperation, act chemically orphysi cally upon the calcic sulphate and render it more compact, harder,and less soluble, and that the oxalic acid acts in like manner upon theimpurities or matters of othercomposition, (carbonates, &c.,) which areusually contained in greater or less quantities in native gypsums, andproduce like indurating effect upon them, though the salts may have aniudurating action upon the impurities present, and the acids may act inlike manner more or less upon the calcic sulphate.

By the alternate application of the sulphate of iron and bichromate ofpotash in the two baths as above described a beautiful yellowcolorisimparted to the calcic sulphate throughout its mass, which willusually be variegated more or less, however, by irregular lines, veins,or markings of darker shades, and perhaps of other tints, due probablytoimpurities present in the calcic sulphate. The article (certaldite) thussecured is a valuable material for various uses in the arts, both onaccount of its beautiful and highlyornamental appearance and also onaccount of its high degree of hardness, insolubility, and susceptibilityof taking a line polish.

When the article has been treated in the bath as above described it isremoved and dried by GXPOSUIB t'othe sun, or to an equivalentfurnace-heat, for one or two hours, or by ordinary atmospheric exposurefor two or three days, when it is ready for polishing and such othermani 'iulation as may best tit it forits intended use, which may be doneby any of the methods practiced in kindred arts.

No claim ismade herein to the process set forth, as that, with variousmodifications of the same, as circumstances may require, forms thesubject-matter of the first application herein referred to. Neither do Ilimit my present invention to the particular way herein described ofapplying it, though I now believe this way or process to be the best. Ialso believe the proportions of ingredients which I have named informing my improved composition to be the best for the purposes stated,and, among others, to secure a uniform degree of hardness and colorthroughout the mass of the article. If the solutions be very strong,thereis great dauger of rendering the surface of the article hard veryquickly, and thereby preven ting proper action of the bath upon theinterior substance of the article; or if the solutions be very weak toomuch time is required, and even then a proper degree of hardness,dcnsity,aud insolubility is not secured; also, by the conjoint action ofall the elements of the two baths much better results are secured,especially upon native gypsums, than by solutions formed of a part ofthe elements. For these reasons I prefer to employ all the elements ofthe two-part composition in substantially the proportions named; butsuch limits, though affording the best results, may be varied orexceeded somewhat and still obtain favorable results under skillfulmanipulation, and all such modifications employing the elementssubstantially as herein described in about the proportions set forth Iconsider as coming within my invention and claim.

I claim as my invention- The two-part composition herein described fortreating dehydrated gypsum in separate baths, each part consistingsubstantially of the following elements: in the first part water andsulphate of iron, and in the second part water, alum, oxalic acid, andbichromate ot' potash, in about the proportions set forth.

In testimony whereof I have hereunto setiny hand.

RAPHAEL JOSIA.

Vitnesses:

}UIDo PAN'IALIONY, 1t. H. W HrrtrLEsEv.

